Refrigeration



June 12, 1945. V, Q DRE|ER 2,377,926

REFMGERATION Filed July 22, 1941 2 SheetsSheet l INVENTOR 70,? 6.[Lef/5,6

BY I y @yat/L Moige 0M Jwma 12g, 199%5. Y v. ai.; mFfel-:z 2,377,926

Filed July 22, 3.942. 2 Sheets-Sheet 2 INVENTOR Vz'czar Dreier BY @MMATTORN EYS Patented June 12, 1945 REFRIGERATTON 'victor G. Dreier,Evansville, 1nd., assigner to Servel, Inc., New York, N. Y., acorporation of Delaware Application July 22, 1941, Serial No. 493,487

6 Claims.

This invention relates to refrigeration and more particularly todefrosting the cooling element of a refrigeratori It is an object ofthis invention to provide for the automatic defrosting of a coolingelement of a refrigeration system `when an objectionable amount of frostor ice has accumulated on the cooling element. A further object is toprovide automatic means to defer the initiating of the defrostingoperation if this loperation would normally start during a period ofactive use of the refrigerator. A further object is to provideQ efcientand dependable means to control the defrosting operation so that it willoccur at a time when it will interfere least with the normal use of therefrigerator;

The above and other objects and advantages of the invention will beapparent in the following description taken in connection with theaccompanying drawings which forms a part of this specication and inwhich:

Figure 1 is a more or less schematic view partly vention is applied to arefrigeration unit like that described in a copending application ofCarl T. Ashby, Serial No. 306,258, filed November 27, 1939, entitledRefrigeration; this application has matured into Patent No. 2,285,884.granted June 9. 1942. Accordingly, that patent is incorporated which isheated by a gas flame whereby liquid is raised in the generator througha tube 3l by vapor liquid lift action to the top of standpipe 32. Theliquid flows back down the standpipe and the expelled vapor passes fromthe top of the standpipe through a; conduit 33 to the lower chamber ofan analyzer 28 where it passes in contact with the liquid flowing to thegenerator. In the analyzer, the expelled vapor passes through tube 34 tothe upper chamber 35 and thence through conduit 31 to the rectifier 38where the remaining water vapor is condensed. The pure refrigerantvvapor passes to the condenser 'H4 where it is condensed and the liquidliowsto the top of the cooling element Ill which is filled with hydrogengas.

the hydrogen gas flows back through the heat exchanger I9 to the coolingelement I0. 'Ihe absorbent liquid is delivered to the top of theabsorber Il from the generator through the conduit 2|, heat exchanger2B, and conduit 4I, and

herein, and referencemay be had thereto for a more detailedconsideration of certain features of the apparatus. related to thecopending application of Fritz A. Hedman, Serial No. 406.075, filedAugust 9, 1941, entitled Refrigeration Referring to Figure 1 of thedrawings. an evaporator or cooling element l0 is disposed in arefrigerated space I5 which isA the food storage compartment of adomestic refrigerator the thermally insulated cabinet of which isindicated aty I'I.. At the right. cabinet I8 is provided with-a door I8,and at the bottomof the cabinet and at the left are positioned the otherelements of aheat operated absorption refrigerator.

'I'he present application is alsoV is the liquid from which therefrigerant vapor was initially separated in the generator. 'I'heabsorbent liquid which -is in the form of strong liquor cools in thebottom 'of the absorber and returns to the generator through conduit 25,heat exchanger 26, conduit 21, analyzer 28, and conduit 29. The absorberis cooled by a secondary heat exchange system formed by coil 42connected through conduits 43 and 44 to looped coil 45.

As is well known in the art, there is a tendency for ice to accumulateupon the cooling element of a domestic refrigerator, and inthisvembodiment, when excessive ice has accumulated, it is removedbysupplying hot vapors to the cooling element Ill. The process ofremoving this ice or frost is referred to as defrosting Referring toFigure 2. mounted at the left along the side of cooling element Ill andspaced therefrom is `a baffle plate 8. and atthe right is a similarbaiiie plate 6. During normal operation the air within chamber I5circulates naturally over the cooling element and is maintained in itsrefrigerated condition. Mounted at the top of the refrigerator near thefront (see Figure 1) is a light directing assembly, indicated at 5 andcomprising a bulb l. a thermally insulating lens 3, and a reflector 4'.The light from the bulb is reflected downwardly and toward the rear ofthe refrigerator so that a Here the refrigerant evaporates to give thecooling effect and. diuses into the hyray of light passes betweencooling element I and baille plate 8 in the manner shown in Figure 2. Inline with this ray of light is the sensitive element of a photoelectriccell unit 2 which includes a relay switch which is normally held open.'This relay switch is in series with a heating coil 1, and when therelay switch is closed,

' the heating coil is connected through a pair of leads 9 to a suitablesource of electrical current. When this heating coil is energized, thedefrosting operation is carried on by passing hot vapor to the coolingelement in the manner outlined in the patent of Carl T. Ashby.

Accordingly, referring again to Figure 3, the central portion of thecooling element lil is connected through a conduit 49 having a U-trap 50therein to the' top of the standpipe 32, and when there is no liquid intrap 50, hot vapor may pass directly from the top of standpipe 32 intothe cooling ,element I8. However, except when defrosting is beingcarried on, trap 58 is filled with liquid and there is no ow throughconduit 48. The bottom of trap 50 is connected to one end of a trap 60,the other end of which is connected through a conduit to the bottom ofrectifier 38. A dam 52 extends across the rectier at the left of conduit5 I. with the result that liquid which is condensed in rectifier 38flows into conduit' 5| and thence through trap 60 to trap 50. Duringnormal operation, the liquid collects in trap 50 to the level indicatedby the broken line a I, and liquid above this level ilows down conduit49 into the top of standpipe 32. With trap 50 thus filled, there is noflow of gas from standpipe 32 through conduit 49 to the cooling elementI0 and the normal cycle is carried on as outlined above.

Surrounding `conduit 5| is the heating coil 1 which is energized to pumpor lift the liquid out of conduit 5| and from trap 50 through trap 60.When the cooling element l0 is to be defrosted, this coil 1 isenergized, and as a result, the liquid is pumped from the top of conduit5| into conduit 31 with the result that liquid drains from trap 50 intotrap 60. Thus, conduit 49 and trap 50 are freed of liquid and the hotvapors flow from standpipe 32 to cooling element I0. The size andlocation of heating element 1 and the depth of trap 60 are such thatliquid remains in trap 60 when heating element 1 is energized andcooling element l0 is being defrosted. The amount of this liquid issuilicient to prevent the flow of vapors through conduit 5I and trap 60and all of the vapors flow through conduit 49 to cooling element I0.When the defrosting operation is completed, coil 1 is deenergized andliquid again collects in traps 60 and 50 with the result that the normalrefrigeration cycle is restarted.

When there is light radiation on the sensitive element of thephotoelectric cell, the relay switch of the photoelectric cell unit isheld open so that the heating coil is not energized, and the defrostingoperation is not initiated. Thus, the relay of light from the lightdirecting assembly 5 (Figure 1) plays upon the photoelectric cell andthus holds the relay switch open until an excessive amount of iceaccumulates in the space between cooling element I0 and baille plate 8;at this time the ice cuts off the ray of light so that the relay switchis no longer held open by Preferably the defrosting operation is carriedon when defrosting would be most convenient to the user of therefrigerator. As stated in .the above mentioned application of Fritz A.Hedman, the user of the cabinet ordinarily has no need nor necessity togain frequent access into the food storage compartment in the night.Accordingly, the defrostlng operation is carried on only during thenight when there is no light radiation at the exterior of therefrigerator. To obtain this result, a window l2 is provided in the topof the refrigerator cabinet, and a thermally insulating lens assembly |4is. mounted in this window to direct light from the exterior of therefrigerator onto the sensitive element of the photoelectric cell unit.When there is light at the exterior of the cabinet, the ray of lightwhich is directed from window l2 prevents the initiating of thedefrosting cycle even though ice has accumulated on the cooling elementsuillciently to cut ofi the ray of light from the light directingassembly 5.

Thus, during lnormal operation the refrigeration cycle is carried on,and regardless of the presence of light at the exterior of therefrigerator, the ray of light from the light directing assembly 5 iseffective to hold the relay switch open and prevent the energization ofheating coil 1. When suiiicient ice accumulates to intercept the beam oflight from the light directing assembly, the relay switch is closedunless light is entering window l2, and if light is entering window I2,the relay is not closed. When neither ray of light strikes the sensitiveelement of the photoelectric relay unit, the relay switch is closed sothat the heating coil 1 is energized and the defrosting operation isinitiated.

While I have shown and described one embodiment of my invention, it willbe apparent to those skilled in the art that modifications and changesmay be made Without departing from the spirit and scope of theinvention. Thus, the photoelectric cell unit may control any type ofdefrosting mechanism, whether it be on an absorption type or compressiontype refrigerator.

o Furthermore, the defrosting operation may be of the type hereindisclosed where the ice is melted from the cooling element by heatedvapors, or it may be merely the act of disconnecting the refrigeratorfrom vits source of power. I therefore do not wish to be limited to theembodiment shown in the drawings'and described in the specication andaim in the following claims to cover all of the modifications andchanges which fall within the true spirit and scope of the invention.

I claim:

1. In refrigeration apparatus, the combination of, a refrigeratorcabinet, a refrigeration unit including a cooling element positioned insaid cabinet, a baflie means extending along the side of said coolingelement in spaced relationship with respect thereto to thereby form agap between the baille means and the cooling element, means directing alight ray through said gap, a photoelectric cell unit positioned inthepath of the light ray produced lby said light ray directing means, anddefrosting means controlled by said photoelectric cell unit and.effective to initiate defrosting of said cooling element when the, lightray is intercepted by ice forming in said gap.

2. Apparatus as claimed in claim 1 and including means constituting awindow through which light from the exterior of said refrigeratorcabinet is directed onto said photoelectric cell unit to prevent theinitiation of the defrosting means when there is light at the exteriorof the refrigerator cabinet.

3. In refrigeration apparatus, the combination of, a householdrefrigerator including a thermally insulated cabinet and a refrigerationunit having a cooling means positioned in the top of said cabinet, meansto effect defrosting of said cooling element, a light directing assemblypositioned above the forward end of said cooling element including alens unit and a light unit for directing a ray of light downwardly andrearwardly inet including a lens assembly directing light from theexterior of the cabinet onto said photoelectric cell unit, and controlmeans associated with said photoelectric cell unit responsive -to theinterruption of the ray of light from said light assembly unit by frostaccumulating on said cooling element and to the absence of light fromthe exterior of the refrigerator to initiate the defrosting operation bysaid defrosting means to defrost said cooling element.

4. In a refrigerator including a cooling element subject to theformation of frost or ice thereon during the normal operation of therefrigerator, and structure to modify the operation of said refrigeratorto effect defrosting of said cooling element 'to cause melting of thefrost or ice accumulated thereon, a control device associated with saidmodifying structure including sensitive means responsive to theprojection of a ray thereon and effective to prevent the operation ofsaidmodifying structure when the ray is projected thereon, said controldevice including means to project a ray upon saidsensitive means along apath, the formation of a' predetermined iayer of frost or ice on saidcooling element being adapted to interrupt the ray projected along saidpath to render saidy control vdeviceineifective to prevent .defrostingfrom being initiated.

defrosting the cooling element by reducing the normal ow of liquidrefrigerant to the cooling element and introducing hot vaporo'usrefrigerant into thecooling element to cause defrosting of said coolingelement, projecting a ray along a path adjacent to the cooling element,eiecting the defrosting when the rayiis blocked by a `layer of frost oricc on said cooling element and restricting the defrosting operation solong as the light intensity in the vicinity of the food storage cabinetis at or above a predetermined value.

6. In refrigeration apparatus, the combination of a refrigeratorcabinet, a cooling element positioned therein, means to defrost saidcooling element, a control means responsive to the interruption by iceformation of a ray passing along said cooling element to initiate theoperation of the defrosting means, and meansto prevent the initiation ofthe operation yof the defrosting means when there is light at theexterior of the refrigerator. l

VICTOR G. DREIER.

